Health officials are developing scenarios to test regional smallpox defenses and bioterrorism preparations by late 2004, a senior official at the Centers for Disease Control and Prevention said Thursday.

The "federal standards-based exercise scenarios," will be used to measure how state and regional public health and emergency departments have adopted CDC guidelines and how they would respond to a biological terrorist attack, including one involving smallpox, according to CDC Associate Director for Terrorism Preparedness and Response Joseph Henderson.

The tests are part of the CDC's 2004 action plan for boosting smallpox defenses, Henderson said during a speech to a Health and Human Services Department advisory council. CDC officials also are planning a campaign to raise awareness of the smallpox threat and assuage fears about the vaccine.

Those fears, and the perceived lack of a legitimate smallpox threat, undermined the CDC's nationwide smallpox immunization campaign last year. When President Bush announced the campaign in December 2002, health officials said that they wanted to immunize hundreds of thousands - if not millions - of health care and emergency workers within a year. More than a year later, however, fewer than 40,000 civilian emergency workers have received the vaccine.

The program has essentially ground to a halt. Only 305 people have been immunized since the end of November 2003.

While the immunization program has not been abandoned, CDC officials are now emphasizing smallpox "readiness" and the ability to vaccinate the entire United States in 10 days in the event of an attack. CDC Director Julie Gerberding has repeatedly cited the 10-day vaccination benchmark as a public preparedness goal.

During recent visits, Henderson said he was "extremely impressed" by the biological defense preparations of New York and Washington states. He said, however, that officials must conduct testing to ensure that the emergency planning would stand up in a stressful situation.

Henderson also acknowledged that not all states have made such progress, and he said that CDC officials are examining ways for the federal government to assist states that "just can't seem to get their arms around" the smallpox preparation. That problem could soon become exacerbated as CDC smallpox funding runs dry.

CDC funneled $100 million for smallpox preparedness to states in fiscal 2003, but that was a one-time budget allocation. Henderson said that money had produced "a good return," but states could now potentially struggle with their biological defenses.